1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * Copyright (c) 2021, Microsoft Corporation. 3 * Copyright (c) 2021, Microsoft Corporation.
4 * 4 *
5 * Authors: 5 * Authors:
6 * Beau Belgrave <beaub@linux.microsoft.com> 6 * Beau Belgrave <beaub@linux.microsoft.com>
7 */ 7 */
8 8
9 #include <errno.h> 9 #include <errno.h>
10 #include <sys/ioctl.h> 10 #include <sys/ioctl.h>
11 #include <sys/mman.h> 11 #include <sys/mman.h>
12 #include <sys/uio.h> <<
13 #include <fcntl.h> 12 #include <fcntl.h>
14 #include <stdio.h> 13 #include <stdio.h>
15 #include <unistd.h> 14 #include <unistd.h>
>> 15 #include <asm/bitsperlong.h>
>> 16 #include <endian.h>
16 #include <linux/user_events.h> 17 #include <linux/user_events.h>
17 18
>> 19 #if __BITS_PER_LONG == 64
>> 20 #define endian_swap(x) htole64(x)
>> 21 #else
>> 22 #define endian_swap(x) htole32(x)
>> 23 #endif
>> 24
>> 25 /* Assumes debugfs is mounted */
18 const char *data_file = "/sys/kernel/tracing/u 26 const char *data_file = "/sys/kernel/tracing/user_events_data";
19 int enabled = 0; !! 27 const char *status_file = "/sys/kernel/tracing/user_events_status";
20 28
21 static int event_reg(int fd, const char *comma !! 29 static int event_status(long **status)
>> 30 {
>> 31 int fd = open(status_file, O_RDONLY);
>> 32
>> 33 *status = mmap(NULL, sysconf(_SC_PAGESIZE), PROT_READ,
>> 34 MAP_SHARED, fd, 0);
>> 35
>> 36 close(fd);
>> 37
>> 38 if (*status == MAP_FAILED)
>> 39 return -1;
>> 40
>> 41 return 0;
>> 42 }
>> 43
>> 44 static int event_reg(int fd, const char *command, long *index, long *mask,
>> 45 int *write)
22 { 46 {
23 struct user_reg reg = {0}; 47 struct user_reg reg = {0};
24 48
25 reg.size = sizeof(reg); 49 reg.size = sizeof(reg);
26 reg.enable_bit = 31; <<
27 reg.enable_size = sizeof(*enabled); <<
28 reg.enable_addr = (__u64)enabled; <<
29 reg.name_args = (__u64)command; 50 reg.name_args = (__u64)command;
30 51
31 if (ioctl(fd, DIAG_IOCSREG, ®) == - 52 if (ioctl(fd, DIAG_IOCSREG, ®) == -1)
32 return -1; 53 return -1;
33 54
>> 55 *index = reg.status_bit / __BITS_PER_LONG;
>> 56 *mask = endian_swap(1L << (reg.status_bit % __BITS_PER_LONG));
34 *write = reg.write_index; 57 *write = reg.write_index;
35 58
36 return 0; 59 return 0;
37 } 60 }
38 61
39 int main(int argc, char **argv) 62 int main(int argc, char **argv)
40 { 63 {
41 int data_fd, write; 64 int data_fd, write;
>> 65 long index, mask;
>> 66 long *status_page;
42 struct iovec io[2]; 67 struct iovec io[2];
43 __u32 count = 0; 68 __u32 count = 0;
44 69
>> 70 if (event_status(&status_page) == -1)
>> 71 return errno;
>> 72
45 data_fd = open(data_file, O_RDWR); 73 data_fd = open(data_file, O_RDWR);
46 74
47 if (event_reg(data_fd, "test u32 count !! 75 if (event_reg(data_fd, "test u32 count", &index, &mask, &write) == -1)
48 return errno; 76 return errno;
49 77
50 /* Setup iovec */ 78 /* Setup iovec */
51 io[0].iov_base = &write; 79 io[0].iov_base = &write;
52 io[0].iov_len = sizeof(write); 80 io[0].iov_len = sizeof(write);
53 io[1].iov_base = &count; 81 io[1].iov_base = &count;
54 io[1].iov_len = sizeof(count); 82 io[1].iov_len = sizeof(count);
>> 83
55 ask: 84 ask:
56 printf("Press enter to check status... 85 printf("Press enter to check status...\n");
57 getchar(); 86 getchar();
58 87
59 /* Check if anyone is listening */ 88 /* Check if anyone is listening */
60 if (enabled) { !! 89 if (status_page[index] & mask) {
61 /* Yep, trace out our data */ 90 /* Yep, trace out our data */
62 writev(data_fd, (const struct 91 writev(data_fd, (const struct iovec *)io, 2);
63 92
64 /* Increase the count */ 93 /* Increase the count */
65 count++; 94 count++;
66 95
67 printf("Something was attached 96 printf("Something was attached, wrote data\n");
68 } 97 }
69 98
70 goto ask; 99 goto ask;
71 100
72 return 0; 101 return 0;
73 } 102 }
74 103
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